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/*
 *
 *
 *
 *
 *
 * Copyright (c) 2000 World Wide Web Consortium,
 * (Massachusetts Institute of Technology, Institut National de
 * Recherche en Informatique et en Automatique, Keio University). All
 * Rights Reserved. This program is distributed under the W3C's Software
 * Intellectual Property License. This program is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE.
 * See W3C License http://www.w3.org/Consortium/Legal/ for more details.
 */

package org.w3c.dom.traversal;

import org.w3c.dom.Node;
import org.w3c.dom.DOMException;

/**
 * <code>NodeIterators</code> are used to step through a set of nodes, e.g. the set of nodes in a
 * <code>NodeList</code>, the document subtree governed by a particular <code>Node</code>, the
 * results of a query, or any other set of nodes. The set of nodes to be iterated is determined by
 * the implementation of the <code>NodeIterator</code>. DOM Level 2 specifies a single
 * <code>NodeIterator</code> implementation for document-order traversal of a document subtree.
 * Instances of these <code>NodeIterators</code> are created by calling
 * <code>DocumentTraversal</code><code>.createNodeIterator()</code>. <p>See also the <a
 * href='http://www.w3.org/TR/2000/REC-DOM-Level-2-Traversal-Range-20001113'>Document Object Model
 * (DOM) Level 2 Traversal and Range Specification</a>.
 *
 * @since DOM Level 2
 */
public interface NodeIterator {

  /**
   * The root node of the <code>NodeIterator</code>, as specified when it
   * was created.
   */
  public Node getRoot();

  /**
   * This attribute determines which node types are presented via the
   * <code>NodeIterator</code>. The available set of constants is defined
   * in the <code>NodeFilter</code> interface.  Nodes not accepted by
   * <code>whatToShow</code> will be skipped, but their children may still
   * be considered. Note that this skip takes precedence over the filter,
   * if any.
   */
  public int getWhatToShow();

  /**
   * The <code>NodeFilter</code> used to screen nodes.
   */
  public NodeFilter getFilter();

  /**
   * The value of this flag determines whether the children of entity
   * reference nodes are visible to the <code>NodeIterator</code>. If
   * false, these children  and their descendants will be rejected. Note
   * that this rejection takes precedence over <code>whatToShow</code> and
   * the filter. Also note that this is currently the only situation where
   * <code>NodeIterators</code> may reject a complete subtree rather than
   * skipping individual nodes.
   * <br>
   * <br> To produce a view of the document that has entity references
   * expanded and does not expose the entity reference node itself, use
   * the <code>whatToShow</code> flags to hide the entity reference node
   * and set <code>expandEntityReferences</code> to true when creating the
   * <code>NodeIterator</code>. To produce a view of the document that has
   * entity reference nodes but no entity expansion, use the
   * <code>whatToShow</code> flags to show the entity reference node and
   * set <code>expandEntityReferences</code> to false.
   */
  public boolean getExpandEntityReferences();

  /**
   * Returns the next node in the set and advances the position of the
   * <code>NodeIterator</code> in the set. After a
   * <code>NodeIterator</code> is created, the first call to
   * <code>nextNode()</code> returns the first node in the set.
   *
   * @return The next <code>Node</code> in the set being iterated over, or <code>null</code> if
   * there are no more members in that set.
   * @throws DOMException INVALID_STATE_ERR: Raised if this method is called after the
   * <code>detach</code> method was invoked.
   */
  public Node nextNode()
      throws DOMException;

  /**
   * Returns the previous node in the set and moves the position of the
   * <code>NodeIterator</code> backwards in the set.
   *
   * @return The previous <code>Node</code> in the set being iterated over, or <code>null</code> if
   * there are no more members in that set.
   * @throws DOMException INVALID_STATE_ERR: Raised if this method is called after the
   * <code>detach</code> method was invoked.
   */
  public Node previousNode()
      throws DOMException;

  /**
   * Detaches the <code>NodeIterator</code> from the set which it iterated
   * over, releasing any computational resources and placing the
   * <code>NodeIterator</code> in the INVALID state. After
   * <code>detach</code> has been invoked, calls to <code>nextNode</code>
   * or <code>previousNode</code> will raise the exception
   * INVALID_STATE_ERR.
   */
  public void detach();

}
